Applications have been known which provide navigation to a user from the user's closest station to a shop, for example. Patent Literature 1 describes a system for, by means of a portable information device including a contactless IC card therein, acquiring entry information from the contactless IC card and providing a route, when the portable information device has passed through a ticket gate, for example. However, the technique described in Patent Literature 1 is a technique for providing information on train transfer based on the entry information, not providing directions such as a user's travelling direction.
As a positioning technique for positioning a user who is moving in real time and providing directions to the user, GPS (Global Positioning System) using a satellite is generally used. However, GPS has a problem that a GPS terminal cannot receive radio waves from the GPS satellite indoors, e.g., in a terminal building or an underground mall, so that it cannot perform positioning for navigation in such environments.
Thus, relative positioning has been proposed as a technique for enabling indoor navigation, which uses a self-contained sensor (such as an acceleration sensor, an angular velocity sensor, or a magnetic sensor). The positioning by the self-contained sensor detects a user's motion (movement variable) with the self-contained sensor and estimates a traveling direction and a traveling speed to measure a movement vector of the user, for example. However, only a relative position can be obtained by the relative positioning, and therefore there is a problem that navigation cannot start before an absolute position is acquired.
Moreover, in the relative positioning, the absolute position cannot be obtained, unless an absolute orientation is identified and the user's moving direction (traveling direction) is determined. Thus, a magnetic sensor is generally used as the self-contained sensor so that the absolute orientation is identified by detecting terrestrial magnetism at a start of the navigation. Especially within the doors, however, there is a problem that a magnetic field is disturbed by an electronic device, building structures, or the like in many cases, and a precise position identification is difficult because of difficulty in precise detection of weak terrestrial magnetism. For overcoming this problem, a technique for acquiring a highly-reliable orientation by a magnetic sensor is described in Patent Literatures 2 to 4, for example.
Patent Literature 1: JP 2002-298169 A
Patent Literature 2: JP 2007-309803 A
Patent Literature 3: JP 2011-047950 A
Patent Literature 4: JP 3837533 B